Medical use of multilayered materials has been disclosed e.g. to provide sustained release or controlled release of oral or transdermal drugs (e.g. U.S. Pat. Nos. 4,451,260, 5,093,200, 5,645,858, 5,662,935, 5,681,583 and 5,332,577), or synthetic skin etc. (e.g. U.S. Pat. Nos. 4,060,081, 5,658,582 and 5,876,742).
Biodegradable polymers (Pitt et al. 1979, Ye and Chien 1996) as well as sol-gel processed silica xerogels (Kortesuo et al. 1999) have been used in controlled drug delivery devices, but their composites have not been used in these applications. Bioactive glass has been utilized in many orthopedic applications (Heikkilä et al. 1995). It is known that bioactive glass promotes bone formation.
It has not been possible to build up devices with elegant drug delivery properties with disclosed methods and materials. The novel combination of e.g. the above mentioned biodegradable materials in multilayered materials makes it possible e.g. to alter delivery properties by using different coating and/or core materials. Multilayered materials enable the incorporation of biologically active agents into bioactive glass. This has been possible only by adsorption, which process is difficult to control.